safe but dont abuse it.
jb4 iso g5 with stock turbos, tuned since 40k now at 100k no problem except water pump and drive belt which I replaced both. also I suggest adding a trunk mount meth kit for added cooling and cleaning engine internals

You're most "safe" aftermarket tunes are the BMW PPK and DINAN. Both match BMW's factory warranty and you can drive into any dealership on the off chance something goes wrong (which are slim to none), and actually have a chance to get support for it. Neither are cheap and they are flash tunes, which essentially means no resale parts (except a few dollars more paid an enthusiast might pay on a private sale for a PPK or DINAN car).
My only problem right now with my DINAN stage 3 is that I MIGHT have lost it when the dealer had to re-program my software to fix a flaky brake sensor, but I am worry free, because I get free re-flashes from any BMW DINAN dealer- for the life of my ownership of the car.
Pay to play.

The short answer is NO. if they were you would have factory warranty still in play if you use one. We can debate this all day long but the fact remains if you use an aftermarket tune, even Dinan your warranty will be voided and your car flagged as tuned. If the tuners were 100% confident in the tune they would back you up with a warranty.

The short answer is NO. if they were you would have factory warranty still in play if you use one. We can debate this all day long but the fact remains if you use an aftermarket tune, even Dinan your warranty will be voided and your car flagged as tuned. If the tuners were 100% confident in the tune they would back you up with a warranty.

You might want to look into Dinan a little bit more - I respectfully disagree. PPK is BMW, so we will take them out of the equation.

So far I have gotten three engine /brake related repairs and service bulletins performed free of charge and under warranty by the dealer.

Yes, your car cannot be CPOed, and if something goes wrong with a Dinan flash or part, which is very rare, Dinan and BMW MIGHT have a little pissing match as to who foots the bill- but within the four-year period that you are under warranty, along with the Dinan's own factory matching warranty, you were free and clear sir.

If you had to ask this question then you probably have some doubt. I've seen some people running it without any problems and other times people having horror stories a couple weeks after installing it. By turning up the boost on your car and stressing the turbos out along with everything that has to do with them, obviously it isn't safe.

No. But neither is driving on the road. Consider this: at any given moment in which are on a two lane highway or any highway really where there is no dividing barrier in the middle of the road, a driver going opposite to your direction, crossing your path, could easily decide to swerve head on to your car, killing you.

Realistically, that is as likely to happen as finding a fifty dollar bill on the ground. What am I trying to say? The risk is there, but the chances of something catastrophic happening to your car is very slim.

You might want to look into Dinan a little bit more - I respectfully disagree. PPK is BMW, so we will take them out of the equation.

So far I have gotten three engine /brake related repairs and service bulletins performed free of charge and under warranty by the dealer.

Yes, your car cannot be CPOed, and if something goes wrong with a Dinan flash or part, which is very rare, Dinan and BMW MIGHT have a little pissing match as to who foots the bill- but within the four-year period that you are under warranty, along with the Dinan's own factory matching warranty, you were free and clear sir.

Dinan Voids BMW warranty Period. Call Dinan and they will tell you that. I respect your opinion but when push comes to shove the car owner is going to pay the price. Any tune outside of BMW will void your warranty on many aspects of your car and most important... the car is flagged by it's VIN as a car to watch to scrutinize. Yes you are free to trust Dinan to pay for whatever their tune might screw up but the question was is JB4 safe/harm free and that answer will always be NO.

Damn, thanks for all the feedback guys. So SAYYYYY something happens to the car and prior to bringing it for warranty repair, I return the flash to stock- would bmw be able to figure out that it may have been flash tuned in order to cause the fault, thus voiding the warranty?

Basically the best thing to do is buy a car cheap and out of warranty, mod the hell out of it, have a little money saved up to repair it if something goes wrong. You'll still be paying a lot less that way than buying a car in warranty, getting a Dinan tune and nothing breaking.

Damn, thanks for all the feedback guys. So SAYYYYY something happens to the car and prior to bringing it for warranty repair, I return the flash to stock- would bmw be able to figure out that it may have been flash tuned in order to cause the fault, thus voiding the warranty?

I do believe the dealer can read shadow codes. JB has the option to clear them I believe.

Well I'm fairly new to the mods. All I have is the bms DCI.
I went to a car show last night and saw another dude with an e93. He advised me to grab the jb4. When I heard it projects 100hp 100tq for $500 I was all for it. Started reading a bit and found some negative stories, got me a little shook lol!

I am in the same boat and I love the way a JB4 335i drives but for the time being I have decided against it. This car is fast already and has been decently reliable I am afraid after getting the tune I will potentially ruin the reliability.

Another less "risky" option to look at is that alpina transmission flash if you have an auto.

I am in the same boat and I love the way a JB4 335i drives but for the time being I have decided against it. This car is fast already and has been decently reliable I am afraid after getting the tune I will potentially ruin the reliability.

Another less "risky" option to look at is that alpina transmission flash if you have an auto.